This is how a police officer described the "horrifying" moment a man allegedly pointed a loaded hunting rifle at him during a verbal confrontation on the side of a rural road in the early hours of the morning.

Tasmania Police Constable Robert Shepherd took the stand in the Launceston Supreme Court on Wednesday to give evidence against Anthony John Knowles, who has been accused of aiming the gun at him.

Mr Knowles, 36, pleaded not guilty to a charge of aggravated assault, with his lawyer claiming on his behalf that he never pointed the gun at the officer and instead pointed it at the ground on the night in question.

Describing the alleged incident, Constable Shepherd told the jury he and another officer were in the Nunamara area in March last year when they noticed a car on the side of the road.

Inside the car they found the defendant and another man, both dressed in camouflage, he said.

It’s alleged the men told the officers they were on their way to work at Scottsdale, but had run out of fuel.

The officers then asked to search the boot of the car and found a blue tarp, meat hooks and rope, the jury was told.

Constable Shepherd said he searched a camouflage backpack and found knives and a glass smoking pipe.

The court heard, it was when the accused was asked “repeatedly” to get out of the car to allow the officers to do a “thorough search”, that Constable Shepherd said he became “aggressive”.

Constable Shepherd told the jury he noticed part of what he believed to be a rifle sticking out from the passenger side footwell, where Mr Knowles was sitting.

Unclipping his holster and beginning to draw his own weapon, Constable Shepherd said he again demanded Mr Knowles to get out the car.

It was then the officer claimed the accused stepped out of the car, with the rifle in his hand.

Constable Shepherd said both he and the second officer had their pistols drawn and were yelling at Mr Knowles to “drop the gun”.

Mr Knowles said “what are you going to do? Come on have a go ya c---” and “shoot me then”, the court was told.

“The only thing that stopped me [from firing] was he had a large calibre hunting rifle … if I had fired [the pistol] and then he fired I’m positive I would have come off worse for wear,” Constable Shepherd said.

When asked how he felt at the time of the alleged confrontation, Constable Shepherd told the jury he was afraid.

“At any stage he could have shot me,” he said.

“It was horrifying … I had a wife that was newly pregnant with our first child.”

Ms Gibson questioned Constable Shepherd about why he didn’t tell the accused to “put his hands up where he could see them” and instead walked around the front of the car where he wouldn’t have been able to see the gun.

“I assumed Mr Knowles wouldn’t be foolish enough to take the gun out of the car with him,” Constable Shepherd said.

The trial before Justice Robert Pearce is expected to continue for about two or three days.